fix(valid-describe): add check for empty arguments (#94)

Fixes #93

Author: with-heart

Diff for: rules/__tests__/valid-describe.test.js

@@ -71,6 +71,16 @@ ruleTester.run('valid-describe', rule, {
         },
       ],
     },
+    {
+      code: 'describe()',
+      errors: [
+        {
+          message: 'Describe requires name and callback arguments',
+          line: 1,
+          column: 1,
+        },
+      ],
+    },
     {
       code: 'describe("foo", async () => {})',
       errors: [{ message: 'No async describe callback', line: 1, column: 17 }],

Diff for: rules/valid-describe.js

@@ -37,6 +37,13 @@ module.exports = {
     return {
       CallExpression(node) {
         if (isDescribe(node)) {
+          if (node.arguments.length === 0) {
+            return context.report({
+              message: 'Describe requires name and callback arguments',
+              loc: node.loc,
+            });
+          }
+
           const name = node.arguments[0];
           const callbackFunction = node.arguments[1];
           if (!isString(name)) {